fix(agent-names): use HTTP-header-safe display names and config keys for API calls (#3138)

Display names with parentheses like 'Atlas (Plan Executor)' cause HTTP
header validation errors in x-opencode-agent-name. This was blocking
Atlas/Prometheus from working via /start-work and auto-retry.

Changes:
- Display names: parens -> dashes ('Atlas - Plan Executor')
- Hooks (start-work, no-hephaestus-non-gpt, no-sisyphus-gpt): use
  config keys ('atlas', 'sisyphus', 'hephaestus') for agent API fields
- auto-retry: use config key instead of display name for promptAsync
- agent-override-protection: handle dash-suffix normalization
- Updated all test expectations to match new format

Closes #3138

src/hooks/start-work/start-work-hook.ts

@@ -85,12 +85,12 @@ export function createStartWorkHook(ctx: PluginInput) {
     const activeAgent = isAgentRegistered("atlas")
       ? "atlas"
       : "sisyphus"
-    const activeAgentDisplayName = activeAgent === "atlas"
-      ? getAgentListDisplayName(activeAgent)
-      : getAgentDisplayName(activeAgent)
+    const activeAgentDisplayName = getAgentDisplayName(activeAgent)
     updateSessionAgent(input.sessionID, activeAgent)
     if (output.message) {
-      output.message["agent"] = activeAgentDisplayName
+      // Use config key for agent field to avoid HTTP header validation issues
+      // Display names like "Atlas (Plan Executor)" contain parens that are invalid in headers
+      output.message["agent"] = activeAgent
     }
 
     const existingState = readBoulderState(ctx.directory)